If you prefer to view this article in PDF form, click here.

The nonoperative management of shoulder instability

Here are techniques for making an accurate diagnosis, managing patients conservatively without surgery, and safely returning them to their premorbid level of activity.

Vinh Dang, MPAS, PA-C

The author works at Sports and Orthopaedic Specialists in Minneapolis, Minnesota, specializing in shoulder and elbow injuries. He is also a guest lecturer for the Augsburg College PA program in Minneapolis, Minnesota. He has indicated no relationships to disclose relating to the content of this article.

The shoulder is the most mobile joint in the human body because of the articulation of the humeral head in a relatively shallow glenoid fossa. This articulation allows the shoulder to rotate up to 180 degrees in three different planes. However, this versatility puts the shoulder at increased risk for injury, particularly instability.

Shoulder instability refers to a range of disorders characterized by dislocation, subluxation, and laxity. A dislocation is a complete loss of humeral articulation from the glenoid fossa. Primary dislocations are usually the result of trauma, and recurrent dislocations can stem from traumatic or atraumatic events. Subluxation is defined as a partial loss of the humeral articulation within the glenoid where symptoms are reproduced. Subluxations can be caused by traumatic or atraumatic incidents. Laxity refers to generalized looseness of the glenohumeral joint and other joints, where patients are asymptomatic. By understanding shoulder anatomy, different forms of instability, and nonoperative treatments, the PA can make informed decisions for orthopedic referral.

Shoulder girdle anatomy

Four joints make up the shoulder girdle: the scapulothoracic, glenohumeral, acromioclavicular, and sternoclavicular joints (see Figure 1). The two critical articulations for stability are the glenohumeral and the relatively underrecognized scapulothoracic joints.

The scapulothoracic joint is the articulation of the scapula to the thorax via the rib cage. Its stability cannot be overemphasized; it is crucial for correct glenoid positioning and therefore for stability of the humeral head in the glenoid. In other words, it provides a stable foundation for the ball to sit on the tee.

The glenoid fossa is relatively shallow and thus lends little bony support for stability of the humeral head. The stability of the glenohumeral joint is dependent on the surrounding soft tissues: ligaments, cartilaginous labrum, and rotator cuff muscles. The ligaments and labrum act as static stabilizers by acting as concave structures to deepen the glenoid fossa. This function is important for glenohumeral static stability.¹

The dynamic stabilizers include the rotator cuff muscles and surrounding larger muscles that provide scapular stability (serratus anterior, latissimus dorsi, rhomboids, trapezius, and pectoralis). The rotator cuff acts as a humeral head depressor to maintain the humeral head in the glenoid throughout the wide range of its motion.¹

Types of instability

The classification of glenohumeral joint instability includes degree, frequency, etiology, and direction.² Degree refers to dislocation, subluxation, or laxity. Frequency of instability can be classified as primary or recurrent. Glenohumeral joint instability can be caused by traumatic or nontraumatic events. Instability is described as unidirectional or multidirectional. Unidirectional instability can be further categorized into anterior versus posterior instability, while multidirectional instability (MDI) refers to instability in two or more planes and is usually associated with generalized laxity (see Table 1).

Anterior injury Anterior instability is the most frequent type of unidirectional instability, occurring in up to 98% of shoulder dislocations.³ The typical cause of a primary anterior shoulder dislocation is a traumatic injury resulting from a collision or fall with the arm in abduction and external rotation. Recurrent anterior instability can be related to traumatic or nontraumatic incidents with the arm in this classic position. Athletes aged 18 to 25 years are most susceptible, in part because of their increased flexibility and range of motion, greater levels of physical activity, and tendency to participate in multiple sports.⁴

In acute anterior shoulder dislocations, the patient will be cradling the arm in slight abduction and external rotation. The person will complain of significant pain, worsening with any attempt to move the arm, and will resist abduction and internal rotation. Simple inspection can often make the diagnosis: a bulge may be present over the anterior shoulder with an area of emptiness beneath the acromion where the humeral head normally resides.⁵

Posterior injury Posterior instability occurs in approximately 2% to 5% of all cases of shoulder instability.⁶ Although dislocations can result, subluxations are much more common. The mechanism of injury is typically a force along the arm while in internal rotation and slight adduction. Athletes who suffer from this form of instability are typically football offensive linemen whose humeral head is forcibly driven posteriorly during blocking maneuvers. Nonathletes can suffer posterior dislocations from sudden generalized muscle contraction, such as that caused by seizures or electrical shock.

The classic physical finding with a posterior dislocation is an internally rotated arm; there will be a prominence of the humeral head on the posterior shoulder, while the coracoid may look more prominent. The patient will also be unwilling to rotate the shoulder externally due to pain.⁵

Multidirectional instability MDI refers to instability in two or more planes. Most patients who suffer from MDI have vague symptoms with activity, often complaining of “looseness.” A thorough physical examination will typically show generalized laxity in multiple joints. Patients often have hyperextension at the elbows and the ability to touch the thumb to the ipsilateral wrist. A positive inferior sulcus sign is pathognomonic for MDI. Additionally, patients with MDI will often present with weak rotator cuff muscles and scapular dyskinesis, or poor scapular posture.

Acute management

After an acute dislocation, management begins with a neurovascular examination. Test the axillary nerve for pinprick sensation and motor control. If an injury has occurred to the axillary nerve, there will be decreased sensation over the lateral deltoid as well as decreased strength of the deltoid to abduct the arm. This should be documented and attempts to reduce the dislocation should be made.

Shortly after an anterior dislocation, the surrounding muscles begin to spasm, making reduction difficult. There are numerous techniques available to the clinician, but the three most common methods are traction-countertraction, external rotation, and the Stimson method. The clinician should be comfortable with at least two different techniques in case of a failed first attempt. Reductions should be performed slowly. Reduction is successful when the patient has immediate relief of pain and is able to move the arm in the direction he or she was unwilling to before.

Traction-countertraction is probably the most common reduction technique and requires two or more people to perform. There are many variations with the patient either sitting or supine. The clinician provides traction on the affected arm, while another person provides countertraction by pulling on a sheet wrapped around the patient’s torso (see Figure 2).

The external rotation method is probably the easiest to perform. With the patient supine on a bed, the humerus is adducted against the torso and the forearm is flexed at the elbow to 90 degrees. The clinician then slowly and gently externally rotates the arm with little or no traction necessary. Reduction occurs spontaneously as the arm is externally rotated (see Figure 3).

The Stimson method requires the use of weights and a bed. The patient is placed prone with the affected arm dangling off the bed and weights strapped to the wrist and/or forearm. Typically 5 lb is sufficient, but greater weight may be needed for a larger or very muscular patient. The weighted arm then hangs with constant traction on the shoulder. Reduction occurs spontaneously after a few minutes—it may take as long as 20 minutes—when the muscle spasm is overcome by the weight (see Figure 4). Although safe and easy to perform, the Stimson method requires time and patients must be monitored, both of which are drawbacks.

Self-reduction techniques can be taught to patients who are recurrent dislocators. One method is to interlock the fingers and place the hands around the ipsilateral knee. The patient then pushes the knee forward or leans back, and reduction will spontaneously occur.

Posterior dislocations are relatively easier to reduce because the external rotator muscles are not as strong as the internal rotators and adductors, which are involved in anterior dislocations. The clinician applies traction on the arm while it is still in the adducted and internally rotated position. An assistant may need to gently push the humeral head anteriorly back into the glenoid fossa.

Unless reduction is performed immediately either on the athletic field or by self-reduction, most patients will require analgesia, muscle relaxation, and/or sedation. If reduction is not successful with the methods discussed, the patient may need reduction performed with general anesthesia.

Subacute management

Physical examination A thorough examination is needed after any reduction. Reevaluate and document the axillary nerve. Next, test the patient’s affected shoulder for rotator cuff strength compared to the nonaffected shoulder. Associated rotator cuff tears are infrequent before age 40 years,⁷ but evaluating the primary internal rotator, the subscapularis, is crucial in anterior dislocations.⁸ You cannot miss a full thickness tear of the subscapularis; it is easily revealed by the abdominal push test, which is very specific and sensitive for a subscapularis tear. Have the patient put his hand on his abdomen; then have him resist while you try to pull the hand away. Comparing this strength test to the contralateral shoulder will rule out a subscapularis tear (see Figure 5). You can also confirm the integrity of the subscapularis using the lift-off test behind the back (see Figure 6). If you suspect a tear, refer the patient to an orthopedic surgeon for evaluation and possible repair.

Imaging studies The question of when to obtain radiographs is controversial. A good history and physical examination can assist you in deciding whether to get radiographs before reduction, after reduction, or both. In the urgent care setting, anteroposterior (AP) and Y-views of the shoulder often confirm the diagnosis and rule out any fractures prior to reduction. An axillary view can also be obtained, especially if posterior dislocation is possible, but this view can be difficult to obtain before reduction because of the patient’s unwillingness to move the arm. Any fractures to the humerus should be immobilized, and orthopedic consultation should be obtained. Many trainers, PAs, or physicians will perform reduction on the field at sporting events before obtaining imaging studies.

Postreduction radiologic studies ordered by the generalist clinician are helpful to rule out fractures of the glenoid (bony Bankart lesion), greater tuberosity, and coracoid and compression fractures of the humeral head (Hill-Sachs lesion). AP, axillary, and Stryker notch views are adequate to rule these out. An orthopedic surgeon should evaluate any fractures. MRI is not necessary unless a tear of the rotator cuff or subscapularis is suspected. If a patient cannot undergo MRI, ultrasonography or arthrography of the shoulder can also rule out rotator cuff tears. The treating orthopedic surgeon may order MRI with contrast at a later time if planning for surgical stabilization.

Nonoperative long-term management

The mainstay of treatment following a dislocation includes immobilization, specific shoulder rehabilitation with a physical therapist, activity restrictions, and possible bracing of the shoulder girdle. The primary care clinician can initiate conservative treatment and maintain this approach until the patient reports recurrent instability affecting activities of daily living or an athlete can no longer compete at his or her current level.

Age is the most significant prognostic factor in determining the rate of recurrence. Hovelius described recurrence rates in 47% of patients aged 12 to 22 years, 34% in patients aged 23 to 29 years, and 13% in patients aged 30 to 40 years.⁴ It is important to exhaust conservative nonoperative treatments in each age group.

Immobilization Traditionally following an acute dislocation, the patient is immobilized or placed in a sling with the shoulder in adduction and internal rotation across the abdomen. The period of immobilization may range from a few days to 6 weeks. In the classic paper by Hovelius, 257 patients aged 12 to 40 years were prospectively randomized into two groups: one was treated with immobilization for 3 to 4 weeks, and the other used slings until the patients were comfortable. The researchers concluded that the two types of immobilization and duration of treatment had no effect on the rate of recurrence. Other studies performed retrospectively have also found no beneficial effect to immobilization in the classic position for up to 6 weeks.²

Interestingly, a preliminary prospective, randomized study by Itoi in Japan immobilized patients for 3 weeks in a nontraditional manner, with the arm in external rotation at 30 degrees rather than internal rotation. Their early reports, with a mean follow-up time of 15.5 months, note a 10% recurrence rate for patients immobilized in external rotation, compared to a 30% recurrence rate for those placed in internal rotation.⁹ Patient compliance is a drawback to the external rotation method.

Exercise rehabilitation A few studies have investigated outcomes of a strict exercise rehabilitation program in the nonoperative management of shoulder instability. In a systematic review of 14 published reports on conservative management, there was a positive trend with respect to conservatively managing shoulder instability. The authors noted that patients experienced positive effects with decreasing recurrence rates, promoting return to premorbid levels of work or athletics and decreasing symptoms associated with instability.¹⁰

Furthermore, a study of 20 midshipmen from the US Naval Academy who suffered primary anterior dislocations and underwent identical shoulder rehabilitation concluded that 75% did not have recurrences and were able to return to full active unrestricted duty and athletic participation.¹¹ More recently, in a contrasting paper comparing nonoperative treatment versus arthroscopic stabilization in first-time shoulder dislocations of active-duty Army personnel, the researchers reported 75% recurrent instability episodes in the nonoperative group. However, of the 75% who had recurrent instability, only half (6 out of 12 patients treated nonoperatively) believed they needed surgery to return to active duty.¹²

Finally, a recent study of in-season athletes with anterior shoulder instability concluded that 90% were able to successfully return to competition for either part or all of their season in an average of 10 days following an acute dislocation. The athletes were treated with a course of physical therapy and no shoulder immobilization. Of those who were able to return to their activities, 37% suffered at least one sport-related recurrent dislocation, while 59% experienced no recurrent episodes. This study did not investigate long-term recurrence rates.¹³

Goals A rigid rehabilitation program tries first to protect the shoulder from provocative motion, followed by gradual muscle strengthening focusing specifically on the rotator cuff and periscapular muscles. The program should be comprehensive, safe, and adapted to the patient’s objectives, whether these are to return to sports or work. Isotonics, isometrics, proprioception, and scapular mechanics are standard ways of achieving near symmetrical strength in the injured shoulder compared to the nonaffected shoulder.

Shoulder braces At any athletic level, the key to returning patients to their sport is the ability to which they can protect themselves and avoid positions of apprehension. Shoulder braces can help to achieve this. In general, the Duke-Wyre brace is useful for nonoverhead throwing contact athletes such as hockey and football players, and a Sully brace is encouraged for overhead throwing athletes (see Figure 7). Although braces may be of some help, patients should be educated in how to prevent future dislocations. Athletes whose activities take them above the ground, such as rock climbers and pole vaulters, should not return to their sport until stabilized; if they dislocate while off the ground, they could fall and sustain serious head and/or spine injuries.

Prognosis

Prognosis after a primary dislocation, even in younger patients, is not as devastating as traditionally believed. It is generally accepted that the younger the patient, the higher the chances for recurrence. However, a thorough and rigid rehabilitation program can return patients to their premorbid states, return athletes safely to competition, and decrease their chances for recurrence. If, after completing a conservative protocol for shoulder instability, the patient continues to have recurrence that affects lifestyle and level of competition, referral to an orthopedic surgeon for discussion of stabilization is warranted.

Acknowledgments

Special thanks to Caroline O’Dell, Kim Woelfel, Andy Todd, and Sports and Orthopaedic Specialists for their encouragement and dedication to research.

REFERENCES

© 2007 Haymarket Media, Inc. and the American Academy of Physician Assistants. All rights reserved.
Use of jaapa.com subject to License agreement. Please read our Disclaimer and Privacy policy.